The proposed research is a multifaceted approach to the development of practical methods of multinuclear magnetic resonance imaging and spectroscopy. The research will be directed principally toward imaging of the 19F nucleus, though the techniques and hardware described are directly applicable to other nuclei. The imaging/spectroscopy experiments will be carried out using a combination of new pulse sequences, new hardware and new signal processing techniques. Developments in each of these areas are necessary to overcome the onerous difficulties inherent in multinuclear in vivo MR. Two new chemical shift imaging sequences are presented which complement ordinary spin warp and gradient echo imaging. These novel sequences eliminate the artifacts associated with large chemical shifts. Gradient pulses for flow compensation are discussed. Designs for switchable coils which can be used for 19F and 1H imaging and localized spectroscopy are also presented. Signal processing techniques are described which can limit the acquisition times and interferogram size of chemical shift experiments. These signal processing techniques may be applied directly to normal 1H imaging and two-dimensional NMR. The 19F imaging experiments will be conducted using perfluoroctylbromide. This compound is an excellent solvent for 02 and CO2 and is reasonably inert, because of these properties it can be used as a "blood substitute". 19F imaging of perfluorocarbon blood substitutes is important, since 19F relaxation rates are strongly influenced by 02 tension. The indirect measurement of pO2 in tissues via 19F MRI would prove extremely important in visualizing lung diseases, ischemic or necrotic tissues, or neoplasms. Perfluoroctylbromide has already been demonstrated as an effective radiographic and ultrasound contrast agent for tumor delineation.